The future of cancer diagnostics: Proteomics, immunoproteomics, and beyond

A new paradigm for cancer diagnostics is that the concept of a biomarker for cancer detection and monitoring is not limited to a single protein but can comprise a proteomic pattern of many individual proteins and the changes this pattern undergoes when tissues transform from a normal to a malignant state. This chapter addresses the issues related to technology development, validation, and quality assurance, and discusses trends in future diagnostic strategies. The importance of mass spectrometry (MS) to the fields of proteomics and cancer diagnostics is undeniable. Although the mass spectrometer can be found in many designs and is used for various functions, nearly all mass spectrometers can be described as the combination of three basic components: the ion source, the mass analyzer, and a detector. The chapter describes the importance of the three most popular ionization techniques for MS: matrix-assisted laser desorption ionization (MALDI), surface-enhanced laser-desorption ionization (SELDI), and electrospray ionization (ESI). ESI MS requires more extensive sample preparation and theoretical expertise than MALDI or SELDI-MS; however, it is the most powerful MS technique available. Diagnostic strategies based on immunoproteomics exploit the natural response of the human immune system by identifying antigens associated with major histocompatibility complex (MHC) class I and class II molecules that are uniquely associated with cancer cells.